When an individual needs to be connected to a person that the individual does not know the phone number of, the individual can call an operator or a secretary and ask to be transferred to the person's phone. Similarly the individual can call an automatic attendant and indicate that the individual wants to be transferred to that person. In either case, the system may rely on features enabled by a private branch exchange (PBX) or Central Office (CO) Centrex equipment.
Such equipment is not always available to reach a person, for example, after business hours. Additionally, the individual may be talking on a phone while driving or be otherwise occupied, and a second person my desire to provide the individual with the number of a third person. To register the new number, the individual may attempt to remember the new number, pull out a pen and write it down while continuing the activity, or stop the activity and write down the number. Any of these methods may compromise the individual's safety when involved in a hazardous activity, such as driving, or may get in the way of other activities.